Surgery would be a lot more dangerous. I have an autoimmune disease as well and two weeks before any surgery I have ever had I have to stop taking all my meds because they dont want my blood to be thin and cause excess bleeding. And since you are on blood thinners already surgery to me would be risky, or at least common senses says it would be. Either way I would ask at the next appt. Good luck.
PS If you decide to go with a cesarean here is a wonderful woman who has a wonderful blog filled with helpful tips for those needing a cesarean and how to plan for one to make it the most enjoyable experience:
http://adventuresindiapering.blogspot.com/
You'll find the tab under her blog header and it says C-Section Info.
If you have a problem with your blood clotting I would think a surgery (and a cesarean is MAJOR abdominal surgery and has many risks including perforating other organs) would be the more dangerous route?
Since they know you're high risk they'll be prepared either way. I'd at least TRY to do a vaginal delivery, but that is just me. Ultimately you need to do what makes you feel more safe. If you feel a cesarean would be quicker, safer and calmer then by all means do it. It isn't as though you're electing a cesarean for a non-medical reason.
However if you want to try for the vaginal delivery experience I don't see, pending other issues, why you couldn't try. Still plenty of time to research, talk to other high risk mommas with blood clotting disorders, get second opinions from medical professionals, etc.
My OB happened to be a high risk OB. Turns out most of his deliveries are c-sections. Worked out well for me because I actually needed one, but after speaking to a nurse who works in that hospital, I learned that he does mostly c-sections. Wonder if I would've had a chance to labor if I hadn't had complications (HELLP and preeclampsia). I am getting the impression that some high risk docs are like this.
My only thoughts are, that if they KNOW in advance that you have this condition, can't they let you labor and be prepared to handle an emergency? I know it's not as convenient for the high-risk doctor, but I would ask both doctors about that. If it's not medically necessary, I would recommend trying to avoid the c-section. Of course, if you need it to your health and safety, it is a blessing. But the recovery is rough and you need help caring for your newborn.